Occassionally followed Makey mini sumo directions

Always wanted to build a robot. Makey in Make magazine seemed easy enough. Since then I've spent way too many hours learning the hard way why I should have followed directions in the first place. First short cut was choosing an old RC for the robot's base, motors and wheels (well tracks). The motors required more AMPs than the sparkfun TB6612FNG dual H-bridge could deliver. I kept adding 9 volt batteries in parallel till the bot moved smoothly. Eventually the H-bridge overheated, melted away insulation on the PING wiring and *POOF*!!! blue smoke and that unpleasant burning smell. Crud! Rework time. Used two L293 H-bridge chips in parallel run fine for about 30 seconds till they overheated.  Two SN754410 h-bridges in parallel running fine so far. Using two seeedo PING $15 knockoffs so I can detected left and right without servo delays. Two lithium cells from an old laptop provide 8.5 volts for the motors. On a full charge I set the bot's PWM speed to 125 (half of full). At 255 it enjoys smashing into everything and I can't catch it. This one time while running object following, it found the dog and instead of following it, the bot drove up and over the dog's back. Currently working on adding compass or 2 axis accelerometer to provide turns in degrees. Then I'd like to add some debugging lights and or sounds, and experiment with programming. 

Currrently considering starting over with better requirements (controlled environment, do a specific task, controlled speed).  Less fun, less frustrating.